In recent years, as light emitting display devices, organic EL devices have been put to practical use, in which a plurality of organic EL elements are arranged in a column direction and a row direction in a matrix on a substrate. In such organic EL devices, the organic EL elements are self-luminous, and therefore visibility is high, and entirely solid-state, and therefore impact resistance is excellent.
In an organic EL device, each organic EL element typically has a structure in which a light emitting layer that includes an organic light emitting material is disposed between an anode and cathode pair of electrodes. When driven, a voltage is applied between the pair of electrodes, holes are injected to the light emitting layer from the anode, electrons are injected to the light emitting layer from the cathode, and the holes and the electrons recombine to emit light. In an organic EL device of a full-color display, such organic EL elements form RGB sub-pixels, a single pixel being formed from a combination of adjacent RGB sub-pixels.
In the organic EL device, a light emitting layer of an organic EL element is typically separated from adjacent light emitting layers of organic EL elements by banks composed of an insulative material. Further, between the anode and the light emitting layer, a hole injection layer, a hole transport layer, or a hole injection and transport layer are interposed as required, and between the cathode and the light emitting layer, an electron injection layer, an electron transport layer, or an electron injection and transport layer are interposed as required. Layers such as a hole injection layer, a hole transport layer, a hole injection and transport layer, an electron injection layer, an electron transport layer, and an electron injection and transport layer are collectively referred to as functional layers.
A method of manufacturing such an organic EL device, as disclosed in Patent Literature 1, includes forming, on a substrate, a plurality of stripe-shaped banks extending in a column direction, and forming a functional layer in a groove region defined by banks. In many cases, the functional layer is formed by a wet method of applying light emitting layer forming ink containing a high-molecular material or a low molecule having a superior capability to form a thin film, to the groove region by an inkjet method. According to this wet method, an organic layer and a light emitting layer can be formed in a large-size panel relatively easily.
Furthermore, in addition to the banks in the column direction, banks in a row direction orthogonal to the column banks are formed on the substrate to define pixel regions adjacent to each other in the column direction in some cases.
Thus, the ink for forming the functional layer is sequentially applied to the entire groove region between the line banks formed on the substrate, so that the functional layer having relatively uniform thickness can be formed in the groove region along its extending direction.